The present invention relates to a device for cutting a safety or seat belt in an emergency when the safety belt cannot be released for some reason.
Seat belts are used particularly in motor vehicles and in airplanes for fastening the occupants on their seats. They consist of a belt of an inelastic high-strength material and restrain the occupants of a seats so as to prevent the occupants from impacting on vehicle interior components during an accident.
A seat belt is closed or opened by means of a belt knuckle which is mounted to the seat or to the vehicle floor and includes generally a plug-in lock and a push bottom release. It is possible however, that during an accident the vehicle body is deformed such that the knuckle release cannot be reached by the vehicle occupant and the seat belt can therefore not be released. It is also possible that the belt knuckle is damaged during an accident such that the release mechanism becomes jammed which also prevents the release of the seat belt. If the seat belt cannot be released for any reason the respective occupant is captured by the seat belt. This may lead to dangerous situations as, after an accident, it is often important that the vehicle occupants rapidly leave the vehicle or can be rapidly taken out of the vehicle. In order to be released from a seat belt when the seat belt knuckle cannot be opened, it is generally necessary to cut the seat belt. However, since a knife or scissors are often not available for that purpose, it has been proposed to arrange a cutting device somewhere reachably in the interior of the vehicle so that the belt can be cut in an emergency. However, such cutting devices are often unreachable after an accident because, as a result of the accident, the occupant strapped into his seat cannot reach the cutting device or the cutting device has been displaced by the accident and is no longer in a reachable place. The use of such a cutting device under high-stress accident conditions however is somewhat problematic since such a cutting device has to be used carefully to avoid injuries to the occupant. However, since in the hectic of an accident, the required care cannot always be taken, the use of such cutting devices may easily lead to injuries of a vehicle occupant.
German OS 28 41 404 discloses a safety belt cutting device for automobiles which includes a housing to be mounted on the safety belt. The housing has a top and a bottom part with a passage fomed therebetween through which the safety belt extends. A blade carrier is slidably supported in the upper housing part with a belt cutting blade projecting therefrom at one end thereof into a slot formed in the lower housing part such that the blade cuts the belt apart if the blade carrier is pulled out of the housing by an operating ring attached to the other end of the blade carrier. After the blade carrier is pulled out of the housing the blade is exposed and care must be taken that no injuries are inflicted to any occupants of the vehicle as those blades have to be and are raser sharp.
German UM G 82 23 436.1 discloses a similar arrangement wherein the housing however is monted on the seat belt at an angle to the longitudinal direction of the seat belt whereby the belt is cut at an angle when the blade carrier is pulled out of the housing. In this case the blade carrier can not be pulled fully out of the housing so that the blade is not exposed after the seat belt is cut and can not cause any injuries to the occupants of the vehicle. Then of course it is not possible to use the blade to cut loose other passengers who, after an accident, might be unable to free themselves from their safety belts.
EP 0 608 467 A1 discloses a safety belt system for automobiles wherein a cutting device is mounted on the belt so that the belt can be cut during an emergency to release an occupant restrained by the belt. In column 1, line 37 reference is made to DE-OS 28 41 404 and it is said in column 2, lines 14-36 that, at one side of the cutting blade, the cutting device disclosed therein is firmly mounted onto the safety belt so that the belt will not be properly released if the device is not correctly mounted onto the belt. In the device of EP 0 608 467 A1 the belt cutting device is therefore firmly mounted centrally onto the belt and two cutting blades are provided, one at each side of the central mounting area of the device. Then the belt is cut at the opposite ends of the belt area which is engaged by the cutting device and the belt is fully cut loose from the device when it is cut during an emergency. However also in this case, the blades are exposed after cutting and might cause injuries to the occupants after they have been used to cut a seat belt during an accident.
It is the object of the present invention to provide a safety belt cutter which is always easily accessible and which can be utilized to free not only the occupant on whose seat belt the cutting device is mounted but also other vehicle occupants in a simple manner and without risks of injuries to the vehicle occupants.